Firenado: What is the apocalyptic twister seen in industrial blaze over Derbyshire?

Flaming cyclonic vortex spotted spinning above burning plastics factory

A “firenado” was filmed by firefighters tackling a huge blaze at a plastics factory in Swadlincote, Derbyshire.

The towering inferno can be seen reaching up to the sky through billowing black smoke, twisting and flickering in the breeze.

Technically known as a "fire whirl", a "firenado" is caused when turbulent wind conditions draw intense rising heat upwards from a burning core.

The flames then meet cooler descending air, which creates whirling eddies that conspire to form a long, spinning vortex resembling a tornado.

This in turn, pulls in debris, dust, ash and combustible gases to fuel its growth.

Strictly speaking, they are not tornadoes because they do not stretch to the cloud line and are driven by surface winds.

Firenados are, however, extremely dangerous - especially if they are transient rather than stationary.

They can reach temperatures as high as 1,090C.

At least 38,000 people were killed in September 1923 when one of them swept through the Hifukusho-Ato district of the Japanese capital Tokyo.

Others have since been recorded in California, Australia and New Zealand.

They most commonly occur as a result of natural wildfires and rarely exceed 50 metres in height, commonly burning out in under a matter of minutes.

However, larger, faster firenadoes can burn for as long as 20 minutes.